An abortion opponent held a rosary and prayed at rally in July 2015 outside a Planned Parenthood clinic in St. Louis. The Missouri Senate has subpoenaed Mary Kogut, the president and CEO of Planned Parenthood of the St. Louis Region and Southwest Missouri, to testify next week at a hearing investigating how the abortion provider handles fetal remains. File photo by Laurie SkrivanThe Associated Press

An abortion opponent held a rosary and prayed at rally in July 2015 outside a Planned Parenthood clinic in St. Louis. The Missouri Senate has subpoenaed Mary Kogut, the president and CEO of Planned Parenthood of the St. Louis Region and Southwest Missouri, to testify next week at a hearing investigating how the abortion provider handles fetal remains. File photo by Laurie SkrivanThe Associated Press

“Ms. Kogut has a right to call witnesses on her behalf, either by way of defense or explanation,” Chuck Hatfield, a lawyer representing Planned Parenthood, wrote in a letter to Senate leadership. “If a hearing occurs, we will do so.”

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At that time they are expected to explain why they should not be held in contempt of the Senate for defying a subpoena demanding documents pertaining to an investigation into how Planned Parenthood handles fetal remains.

If they refuse to show up or provide the documents, the Senate could vote to hold them in contempt, a charge that carries a possible punishment of at least a $300 fine and up to 10 days in jail.

Kogut’s organization — whose St. Louis clinic is the only facility in Missouri that offers abortion services — has said that complying with the Senate’s demands for documents would violate doctor-patient confidentiality and federal privacy laws.

Among the six years’ worth of documents requested by the Senate include any consent forms that must be signed by a patient before an abortion at Planned Parenthood and all written communications related to the disposal of fetal remains.

Sen. Kurt Schaefer, the Columbia Republican who is leading the Senate investigation, said last week that Kogut and Miller would sit before the full Senate on Monday and answer questions as lawmakers determine whether to hold them in contempt.

In his letter, Hatfield wrote that according to the U.S. Constitution, “fundamental rules of fairness apply to a proceeding that could theoretically result in a fine or jail time.” As such, Kogut has the right to call witnesses on her behalf, he wrote.

Kogut asks that the Senate to subpoena former President Pro Tem Tom Dempsey, a St. Charles Republican who established the legislative committee that is requesting the documents from Planned Parenthood.

Kogut also wants subpoenas to be issued to Bill Smith, the sergeant at arms of the Senate who is authorized to bring Kogut to the chamber; and an anonymous third individual whose identity is known by the Senate and who signed the “messenger’s return” of service for the subpoena that was sent to Kogut.

Hatfield said Kogut never was personally served with the subpoena.

“We reserve the right to request additional subpoenas as necessary,” he wrote.

The Senate investigation stemmed from videos that emerged last summer alleging that Planned Parenthood officials sold fetal tissue for profit.

The Missouri Constitution gives the Senate the authority to issue subpoenas and to punish someone for contempt, though records show that lawmakers haven’t brought contempt charges in more than a century.